Device for the automatic adjustment of the composition of bath fluids in apparatus for the chemical cleaning of textile materials and similar matter



April 16, 1963 DEVICE FOR THE AUTOMATIC ADJUSTMENT OF THE COMPOSITION OFBATH FLUIDS IN APPARATUS FOR THE CHEMICAL CLEANING Filed Jan. 10, 1961OF TEXTILE MATERIALS AND SIMILAR MATTER 4 Sheets-Sheet 1 INVENTORATTORNEYS April 16, 1963 E. DH OG 3,085,416

DEvIcE FOR THE AUToMATIc ADJUSTMENT OF THE COMPOSITION OF BATH FLUIDS INAPPARATUS FOR THE CHEMICAL CLEANING OF TEXTILE MATERIALS AND SIMILARMATTER Filed Jan. 10, 1961 4 Sheets-Sheet 2 if 7 36 I 4 @2 6 L7 /4 a; if/z 1 7 w 25 .7 %4\ '49 5 Z a/ 22 2/ U Q Q n W U A; A

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ATTORNEYS Aprll 16, 1963 E. DHOOGE 3,085,416

DEVICE FOR THE AUTOMATIC ADJUSTMENT OF THE COMPOSITION OF BATH FLUIDS INAPPARATUS FOR THE CHEMICAL CLEANING OF TEXTILE MATERIALS AND SIMILARMATTER Filed Jan. 10, 1961 4 Sheets-Sheet 3 INVENTOR zmzze J/i aa z WEEMTE/ ATTORNEYS April 16, 1963 E. D'HOOGE DEVICE FOR THE AUTOMATICADJUSTMENT OF THE COMPOSITION OF BATH FLUIDS IN APPARATUS FOR THECHEMICAL CLEANING Filed Jan. 10, 1961 OF TEXTILE MATERIALS AND SIMILARMATTER 4 Sheets-Sheet 4 e: f7 l v l w I 2% Z J INVENTOR ATTORNEYS3,085,416 DEVICE FOR THE AUTOMATIC ADJUSTMENT OF THE COMPOSITION OF BATHFLUIDS IN APPA- RATUS FOR THE CHEMICAL CLEANING OF TEXTILE MATERIALS ANDSIMILAR MATTER Emile DHooge, Ghent, Belgium, assignor to Ateliers deConstruction Emile DHooge S.P.R.L., Ledeberg, Belgium Filed Jan. 10,1961, Ser. No. 81,716 Claims priority, application Belgium July 15, 19609 Claims. (Cl. 68-13) The invention concerns a device for automaticallyadjusting the composition of the bath in apparatus used for the chemicalcleaning of textile or similar matter, and in particular of clothing andunderclothing.

As is generally known, the method of steaming or chemically cleaningclothing or similar matter consists of a treatment with a solvent ofgreasy substances, naphtha being frequently used, despite the fact thatit is highly inflammable. It is much safer to use other organic solventssuch as Tri (trichlorethylene), Perc or W.S., wherein soapsuds can bedissolved, in order to loosen dirt particles. The clothing is placed inthe drum of the washing machine where it is mechanically rinsed in thecleaning fluid. During this method, the fluid of the bath is beingcontinuously extracted in a closed circuit, to be pumped back into theprocessing chamber after having been passed through a cleaning filter.

it is most important to maintain a constant quality of cleaning, whichmust be independent of the relative humidity of the surroundingatmosphere as well as of the moisture content of the clothing at themoment it is introduced into the machine. In order to obtain theseconditions, it will be necessary to bring the composition of theprocessing bath, and most particularly its water and soap content, to apredetermined value which will be dependent upon the nature of thefabrics being treated, and to maintain this value within narrow limits.

This value is different for the various varieties of fabrics. 'It isgenerally accepted, that loosely woven or knitted woolen fabrics as wellas silk, may be processed at a value of relative humidity no higher than65%. Carded wool, such as mens clothing, can bear up to 78% and purecotton, such as rain clothes for instance, can stand up to 85 or 87% ofrelative humidity. Should these values be exceeded, the materials willfirst start to crease, and next to shrink, to turn feltish, etc. If thecleaning is to be carried outwith maximum efficiency so as to obtainoptimum results and to have the lowest possible need for subsequent spotremoval, it will be essential to maintain with accuracy the relativehumidity which has been determined for the processing of the materialbeing treated.

In the machines and installations used up till now, the desired relativehumidity is obtained by the addition of water to the cleaning fluidduring the cleaning method; this is however only possible when thesolvent has been mixed beforehand with a predetermined amount of soap,suflicient to absorb the required quantity of water. In consequence,this procedure can only be applied in practice to machines which operatewith a permanent and constant concentration of soap, i.e. according tothe charged system.

The required quantities of water are introduced in the circuit at apoint preceding the pump, the water supply being regulated by anelectrically controlled valve in accordance with the instantaneousmeasurement of prevailing humidity. The water thus passes through thefilter, where the filtering powder will be unnecessarily moistened. Inall known systems, the measurement of the humidity is carried out bymeans of an electrolytic meas- 3,085,416 Patented Apr. 16, 1963 uringcell, the increased electric conductivity of which is used as a measurefor the quantity of water to be added to the solution. This presumes,that the solvent, Perc for instance, has a considerably smaller specificconductivity than Water. This is not correct however consider ing thatchemically purse water is also but a very poor electric conductor. Infact, what one measures is mainly the concentration of salts or otherelectrolytes which are dissolved in more or less constant proportions inthe water. Such measurements are consequently most unprecise, as theymay depend uponthe hardness of the Water being used, as well as upon thelargely variable proportions of fatty acids and impurities which arepresent in the solution; they may also be influenced by the nature ofthe soap being used.

A further drawback of these measuring methods consists in the fact, thatin practice it is not easily possible to bring the measuring instrumentinto contact with the liquid of the bath at a point where aforesaidliquid has is effective composition. At such a point the danger wouldexist of the electrodes of the measuring cell being shorted by textilefibres or impurities present in the liquid, thus rendering theinstrument totally useless. It is for this reason that in practice themeasuring cell is introduced at a point in the circuit past the filter.At such a point however, the composition of the liquid is no longer thesame as that in the actual cleaning drum, which represents another causeof Wrong measurements. This is most apparent when moist clothing isintroduced into the machine, the moisture being readily absorbed by thefilter, which at that moment is still quite dry, so that the supply ofwater is adjusted without taking into account the moisture content ofthe introduced clothing. Such poor control can easily give rise tooversaturation and consequently to the known trouble due to this stateof alfairs.

In order to obtain more trustworthy results for these measurements,propositions have already been made to replace the electrolyticmeasuring cell by some hygrometric device, not being in contact with theliquid itself, but merely with the vapour present above the liquid. Forthis purpose hair hygrometers are used, of which the moisture sensitiveelement (hair) is not influenced by the vapours of the solvents, butonly by water vapour. When this element absorbs moisture, its lengthvaries and these variations in length are transmitted to a pointer whichmoves along a graduated scale. This scale may be calibrated for instancefrom 0 to of relative humidity.

. Such a device can now be used to measure the true moisture content ofthe bath liquid and, according to the indications thereof, the quantityof pre-prepared soap and water solution (standard suds) which isintroduced into the circuit can be adjusted.

t The manner in which these principles are being applied in thepropositions known until now has shown many a failure in the practicalapplication thereof, the device having been the cause of a considerableslow-down and (being insufficiently reliable in operation, so that itrequires a constant supervision.

The object of the invention is to provide a new and greatly improveddevice which, by using a hygrometer for determining the moisture contentof the bath fluid,

eliminates the above-mentioned drawbacks and assures an accurate controlof that moisture content in all circumstances.

According to the invention, the device for automatically adjusting thecomposition of the bath in apparatus for the chemical cleaning oftextile or similar materials, where the bath fluid is circulated in aclosed circuit through a filter unit and where water and chemicals areadded to this circulating fluid under control of a device for measuringrelative humidity, is characterized by the fact that the measuringdevice is located in a separate control circuit which is independent ofthe filter unit and in which the cleaning liquid is tapped straight fromthe cleaning drum and fed into the measuring equipment, eventuallythrough an individual filter, whilst the water and washing productswhich are added under the control of this device are poured straightback into the cleaning fluid.

In a particularly favourable form of embodiment according to theinvention, the measuring circuit comprises a mixing device introducedinto this circuit at a point past the measuring equipment, so that thebath fluid circulating in the measuring circuit can be mixed with aquantity of aqueous soap solution controlled by the measuring equipmentbefore it is returned to the cleaning drum. Preferably but a smallquantity of the fluid circulating in the control circuit is actually fedas sample to the measuring equipment, the remainder being led directlyto the mixing device. In order to assure an intimate mixing, this mixingdevice has been built in the shape of a venturi, whereby the bath fluidcoming straight from the cleaning drum passes through the venturi jet,sucking up the fluid returning from the measuring equipment as well asthe controlled amounts of water and soap which are supplied throughseparate pipes. It is moreover an advantage when the supply of water andof cleaning products, generally soap, can be controlled separately andindependently, so that it becomes possible to add soap without water, asrequired for instance when the clothing being introduced alreadycontains sufficient moisture which must be absorbed by the added soapand combined with the solvent.

Preferably the measuring equipment shall consist of a cylindricalcontainer, in the bottom part of which at least one inlet pipe and atleast one outlet pipe are fitted, whilst the top part of the containeris connected to a humidity measuring equipment which is influenced bythe vapour of the bath fluid Without coming into actual contact with thefluid. This measuring equipment may consist of a hygrometer, a hairhygrometer for instance, the sensitive element of which is notinfluenced by the solvent vapours, but exclusively by water vapour. Thishygrometer is equipped with an adjustable contact device, preferablyfitted with an adjusting pointer, which can be set in such a manner asto close an electric contact as soon as a predetermined degree ofrelative humidity is reached, thus completing an electric circuit whichoperates the interruption of the water supply.

When certain materials such as cotton, which need a high relativehumidity, have just been treated and it is required immediatelyafterwards to clean other materials such as light wool which can bearonly a much lower degree of humidity, it is necessary to take intoconsideration, that the vapour pressure of the water in the measuringequipment remains at a high value during a considerable time, so thatthe pointer of the hygrometer will only recede very slowly. The newwashing method may how ever not be started before the pointer of thehygrometer indicates a much lower value of relative humidity, asotherwise the water supply will not be properly controlled.

In order to speed-up this method, a third pipe is fitted to thecylindrical container of the measuring equipment, so as to enable astream of dry air to be passed through the container after each washingmethod, thus driving away the remaining water vapour. The measuringinstrument can then be provided with a second contact device, closing anelectric contact as soon as the humidity indicated by the hygrometerdrops below a pre-determined value, aforesaid contact controlling acircuit which shuts off the dry air supply. Immediately afterwards,fresh water for the new washing method may be supplied.

In order to be sure that the control of the water supply is correctlydependent upon the relative humidity in the bath, it is essential that.the measuring instrument effectively indicates the correct value. Iffor any reason, such as the clogging of the supply pipe for instance,the measuring instrument receives too small a quantity of bath fluid, oreven none at all, this might result in a continuous additional supply ofwater. To prevent such an occurrence, a safety device is incorporated inthe pipe which returns the fluid from the measuring equipment in such -amanner that the water supply can only operate as long as apre-determined quantity of fiuid is being drained from the measuringequipment. Such a safety device could for instance consist of a smallbowl or cup controlling a switching device by means of a lever, and intowhich cup flows the fluid leaving the measuring equipment. The weight ofthe fluid then tilts cup and lever, thus closing the contact device. Asmall hole is provided in the bottom of the cup, so that the fluid candrain away. As long however as a sufficient volume of fluid is evacuatedfrom the measuring equipment, the cup will remain full and the contactclosed. When on the other hand, the flow of fluid through the measuringequipment is restricted for some reason or other, the cup will emptyitself, so that the lever will tilt over and break the contact.

For added safety, signalling lamps or other warning signals can beincorporated in the electric circuits, showing the positions of thevarious contacts and switches. For instance, a red flashing light couldbe installed which lights as long as the water supply is open, providinga permanent check upon the functioning of the hygrometer pointer.

These and further characteristics of this invention will be clarified bythe following more detailed description, which is merely informative andin no way restrictive of the scope of the invention, and by the appendeddrawings in which:

FIGURES 1 and 2 give a schematic representation of the control andadjusting devices as used up till now;

FIGURE 3 represents a schematic view of the control device, appliedaccording to the invention;

FIGURE 4 gives a general sketch of the control apparatus according tothe invention, with indication of the principal elements comprisedtherein;

FIGURES represents a more detailed diagram of the control devicesaccording to the invention;

FIGURE 6 is a large scale representation of the safety devices appliedto the control apparatus;

FIGURE 7 is a more detailed view of the mixing device incorporated inthe control apparatus;

FIGURE 8 is a simplified diagram of the electric control circuits.

In FIGURE 1, which schematically represents a frequently appliedarrangement mainly suitable for the charged system, 1 is the processingchamber of the washing machine in which the laundry contained in drum 2is being rotated. The bath fluid 3 contained in chamber 1 is continuallybeing evacuated through outlet pipe 4 and thus arrives in collector pipe5 from where it is pumped through filter element 7 by means of pump 6 tobe returned into chamber .1 through mlet pipe 8. In order to be able toadd the required quantity of water to the bath, water reservoir 9 isconnected through an electrically controlled valve lib and pipe 11 to apoint in the circuit preceding pump 6. Past filter element 7, anelectrolytic measuring equipment has been introduced in the circuit,capable of deliveringa control potential dependent upon the conductivityof the fluid passing at that point. This control potential is thensufficiently amplified in an amplifying circuit representedschematically at 13 to control valve 10 in such a manner as to close itas soon as theconductivity measured by the electrolytic cell exceeds apredetermined value.-

Besides the drawbacks already mentioned in the introduction concerningthe electrolytic method of measuring the degree of humidity, this systemfurther possesses among others the following disadvantagesi as the wateris introduced at a point preceding filter element 7, the latter as wellas the filtering powder it contains are quite use lessly moistened. Evenif we presume that the measuring equipment is capable of correctlydetermining the 'value of relative humidity, the generated controlpotential would be proportional, not to the relative humidity of thefluid contained in chamber 1, but rather to the relative humidity of thefluid returning to aforesaid chamber, which might have its compositionconsiderably altered by the action of the filter. In fact, any increasein moisture content will only be detected past the filter element withconsiderable delay, so that it could easily happen that the water supplyis maintained longer than it should be. 'Should it be required to washmaterials requiring but little moisture, such as light woolen fabrics,immediately after having processed materials which can bear aconsiderable amount of moisture, the bath fluid having thus to berenewed, the dry solvent will absorb moisture from the filter element,so that in this case as well the results of the moisture measurementswill be wrong. Finally, when working with the charged system, a constantpredetermined soap concentration is present, which already makes itimpossible to adjust the amount of soap used in correspondence with theoptimum supply of water.

In FIGURE 2 a more recent proposition is represented schematically, allcorresponding elements being indicated by the same reference numbers asin FIGURE 1. In this case as well, bath fluid 3 flows through outletpipe 4, collector pipe 5, pump 6, filter element 7 and return pipe 8 ina closed circuit. Samples of the bath fluid are tapped off at a pointpreceding filter element 7 and are led through a simple filter 15 and ahand operated adjusting cock 16 to a cylindrical container 14, to bereturned to the main circuit of the bath fluid through pipe 17. In thetop of container 14 a measuring instrument is located, which undernormal circumstances will be in contact merely with the vapours, butnever with the fluid itself. The measuring instrument used is ahygrometer, and preferably a hair hygrometer.

As long as the degree of humidity remains below the required value,auxiliary pump 10 is operated, being stopped as soon as the relativehumidity has reached the desired value. This auxiliary pump controls thesupply of standard soap solution from reservoir 9 through pipe 11 to apoint in the circuit between collector pipe and main pump 6. t t

This arrangement also has the disadvantage that the added water moistensthe filter content, so that difficulties are encountered as soon aslightwoolen materials have to be washed immediately after cotton fabrics.

In its practical form of embodiment however, this installation showsfurther important drawbacks: The bypass pipe towards the measuringequipment being relatively narrow in view of the volume of the samplesto be tapped off, the hygrometer can but react with considerable delayto the modifications in moisture content of the bath fluid.Consequently, after the introduction of fresh bath fluid or after moistclothing has been placed into the machine, a considerable time elapses,approximately 8 minutes, before the hygrometer indicates the correcthumidity. The supply of fluid to the measuring equipment is moreoverdependent upon the pressure available at the inlet of filter element 7.Should this rise inconsiderately, the flow will become too great so thatthe sensitive element will be rendered inoperative by immersion. Thesystem will be totally out of order as long as this condition prevails.To prevent such an occurrence, the feed must be adjusted manually bymeans of cock 16 at each new washing method.

Also, whenever auxiliary filter 15 gets clogged, standards suds will becontinually added from reservoir 9'. From practical experience it hasbeen found that this filter has to be cleaned several times a day.Moreover, the addition of water and soap in a fixed proportion is farless flexible, considering one is obliged to add water, even when soapalone is required. Finally, there is always a considerable delay betweenthe end of one washing method and the beginning of the next, consideringthat the hygrometer as well as its cylindrical container must first bethoroughly dried before it is possible to obtain a trustworthymeasurement of the new bath fluid. In practice this delay seems to lastapproximately 12 minutes, during which period no fresh water can beadded. Due to all these circumstances, a complete. washing cycle willtake about 20 minutes longer than the actual time required by thewashing method proper.

By applying the dispositions according to the invention, which areschematically represented in FIGURE 3, all these inconveniences aresystematically eliminated, as will be made clear by the followingdescription. As in the known methods previously described, the measuringinstrument in this case is also a hygrometer 12 connected to the top endof a cylindrical vapour chamber 14, which is thus capable of determiningthe relative humidity without being in contact with the liquid itself.This hygrometer is however placed in a circuit which is totallyindependent of main filter element 7, to which circuit water and soapcan be added under control of the measuring equipment without being ableto moisten filter element 7. The bath fluid flowing through outlet pipe18 is pumped by pump 20, through steel wool filter 19 into pipe 21. Thegreater part of this fluid reaches mixing device 24 by means of pipe 22,whilst the remaining part reaches vapour chamber 14 through a muchnarrower pipe 23- and serves as sample for the measuring equipment,finally also flowing back into the aforementioned mixing device 24,through outlet pipe 25 and safety device 26. In this mixing device 24,the bath fluid is thoroughly mixed with the eventually added quantitiesof water and soap supplied from separate reservoirs 27 and 30' throughpipes 29 and 32 respectively, before being poured back into theprocessing chamber through evacuation pipe 33. This addition of waterand soap can be controlled automatically by means of electricallyoperated valves 28 and 31 provided respectively in pipes 29 and 32.

By a proper choice of the diameters of pipes 21 and 22 and of the powerof auxiliary pump 20, a powerful and rapid circulation of the bath fluidcan be obtained. The fluid is thus rapidly brought close to measuringinstrument 12, so that the latter can react without delay to anymodification of the composition thereof. This powerful stream of liquidis further used in mixing device 24 to obtain the intimate mixing of the(fluid with the added quantities of water and soap. The safety device 26is arranged in such a manner as to operate, closing the water supply, assoon as the flow from pipe 25 coming from the measuring equipment ceasesor becomes insutficient.

connected up in such a manner to the supply system of fresh bath fluidas to shut off this supply as soon as the level in processing chamber 1has reached the required height P. The device can also be interconnectedin such a manner with the control circuit as to automatically start pump20 as soon as level P has been reached, after which the control circuitfor the water supply can also be prepared. As is also shownschematically in this FIGURE 5, hygrometer 12 is provided with threepointers 35, 3'6 and 37 which can be displaced along a graduated scalewhich has not been drawn. Among these, pointer 35 is the one which isconnected to the sensitive element, usually a hair, 38, in such a mannerthat it indicates the instantaneous value of water vapour content invapour container 14. Pointers 36 and 37 can be displaced manually alongthe dial graduations, pointer 36 being adjusted to the desired minimumvalue of relative humidity and pointer 37 to the desired maximum value.These pointers :are fitted respectively with contacts 36' and $7, whichcooperate in such a manner with mobile indicator pointer 35 (see FIGURE8), that when this indicator pointer coincides with the lower adjustedvalue, a contact is closed across the secondary winding of a transformer40, and that when aforesaid indicator pointer coincides with the upperadjusted value, a contact is closed across the secondary winding of asecond transfonmer 4-1.

Besides the two previously mentioned pipes 23 and 25, yet a third pipe42 opens up into vapour chamber 14', leading from a dry air supply andbeing fitted with an electrically operated control valve 43. This airpipe is opened up at the end of each washing method, thus supplying astream of dry air which thoroughly dries out the inside of vapourchamber 14 and hygrometer 12. The arrangements are such, that thehygrometer will control valve 43, more particularly by the action ofindicator pointer 35 closing the contact elements 36 provided onadjusting pointer 36, in such a manner that this valve will close andshut off the air supply to pipe 42, as soon as the measured relativehumidity corresponds to the lower adjusted value.

In this case, pipes 22 and 23 are provided respectively with adjustingcocks 39 and 39' in order to be able to adjust the flow through thecorresponding pipes.

Safety device 26 provided in pipe 25 between the measuring equipment andmixing device 24 is represented separately and on a larger scale inFIGURE 6. It mainly consists of a cylindrical container with funnelshaped bottom which leads into outlet pipe 49 returning to mixing device24. In this container, a cup 44 is located under outlet opening of pipe25 and fixed to the end of a lever 45, the latter being free to pivotabout fixed pin 46. The other end of this lever is provided with amercury switch represented symbolically in the drawing by mercury tube47. This mercury switch comprises two independent contacts, shown as 50and 51 in FIGURE 8, which close when the cup tilts down under the weightof the contained fi-uid. When however this cup is empty, or almostempty, the lever will be tipped to the horizontal position by the weightof the mercury tube and eventually of added counter-weights, thusopening the contact. As to the mention of added counter-weights is meantthat the lever includes counter-weights in addition to the mercury tubein case the weight of this mercury tube is not sufficient to hold thelever in its horizontal position when the cup is empty. An evacuationhole 48 is provided in the bottom of cup 44, the flow through thisopening being chosen in such a manner, that as long as a sufficient flowof liquid from the measuring equipment reaches cup 44 from pipe 25, thelevel of liquid will rise in the cup and overflow the edge thereof intocontainer as, the cup thus remaining in its tilted down position. Shouldhowever the flow from pipe 25 cease, the liquid in the cup will drainaway through opening 48, so that the lever will tilt back to thehorizontal position, thereby opening the mercury switch.

The mixing device 24 incorporated according to the invention in theadjusting circuit is shown on a larger scale in FIGURE 7. This mainlyconsists of a cylindrical closed container 52, to the bottom of which afunnel shaped part 53 is fitted, the latter being connected to outletpipe 33' which leads back to processing chamber 1. Pipe 22 leadingstraight from auxiliary pump 29 is terminated by a jet nozzle 54 placedclose to and concentrically with funnel shaped part 53 of the containerbottom. Three pipes 29, 32 and 4-9 open up in the top of cylindricalcontainer 52, the first of which leads via control valve 28 from waterreservoir 27, the second being connected via control valve 31 to thesoap reservoir 36, whilst pipe 49 is the one returning the sample ofbath fluid from the measuring equipment, through safety device 26, tothe mixture. This mixture is next powerfully, sucked up by the venturiaction of jet nozzle 54, by means of which the thorough mixing of thesoap solution with the bath fluid is obtained.

The operation of this complete equipment can now be explained withreference to the wiring diagram of FIG- URE 8. L and L now represent thepower leads which feed the control system through fuses Z.

At the beginning of a washing method, the necessary quantity of solventis introduced into the processing chamber and simultaneously, before therequired level is obtained in aforesaid processing chamber, pump 20 isstarted, thus pumping a continuous stream of fluid through the controlcircuit 21-22--2333. By means of float device 34, the supply of solventis stopped, by a procedure which needs no further explanation, as soonas the desired level P is reached in the washing chamber. A smallportion of the fluid thus set in motion reaches the measuring equipmentthrough the by-pass pipe and then fiows through pipe 25 intothe safetydevice, where it is collected in cup 44, which at the time is still inhorizontal position. Considering that normally more fluid is suppliedthrough pipe 25 than can be evacuated through the narrow opening 48, thelevel of fluid will rise in the cup, until the latter is tilted down bythe weight of the fluid accumulated therein, thus closing contacts 50and 51. The overflowing fluid then returns through pipe 4-9 and mixingdevice 24 into the circuit.

In this manner the measuring equipment is continually fed with a certainquantity of bath fluid and is consequently capable of indicating thecorrect moisture content of the bath. At the same time, the closing ofthe mercury switch has prepared the control circuit for the addition ofwater, which condition is signalled by the lighting of a green pilotlamp 56.

When the clothing which is to be cleaned comes into contact with thesolvent, three cases are possible:

(1) The clothing contains the same degree of moisture as the solvent andno modification of the degree of hu-' midity occurs, so that thehygrometer pointer does not move; I

(2) The clothing is less moist than the bath fluid and absorbs moisturefrom the bath, so that the hygrometer pointer will recede;

(3) The clothing contains more moisture than the bath fluid and givesoff some of it to the bath, so that the hygrometer pointer advances.

The time required to obtain equilibrium between the degree of humidityof the clothing and that of the bath is of the greatest importance.Theoretically one should wait till the hygrometer pointer is at astandstill, before proceeding with the eventual addition of water. Infavourable circumstances this will last at least one minute. Inpractice, with automatic machines, the addition of water is madedependent on the reaching of the desired level in the processing bath,i.e. that no water can be added before the required quantity of solventis available.

The washing bath thus consists of a fixed quantity of solvent which isintroduced into the drum and of which a sample is sent to the hygrometerequipment during at least one minute.

After this adjusting period, Water can be added if required, i.e. if atthat moment the indicator pointer 35 of hygrometer 12 has not yetreached adjusting pointer 37.

In a manner which need not be described here, power is applied toterminals 57 and 57-see FIGURE 8the first of which is directly connectedto the feed of control valve 31 and also via closed mercury contact 50and closed relay contact 60 to the feed control valve 28. Consequentlyboth control valves 31 and 28 are opened, so that soap as Well as wateris supplied to the mixing device 24, which means that these products arefed into the bath fluid in the form of an emulsion, having beenthoroughly mixed. The opening of the water supply is made known by thelighting up of a red pilot lamp 62.

By applying power to terminal 58, current will also flow through relaywinding R3, connected in series with the primary winding of transformer41. Due however to the high impedance of this transformer, the value ofthe current is kept so low, that the relay can not operate. This is thecase as long as indicator pointer 35 of hygrometer 12 has not yetreached the position of adjusting pointer 37. By the addition of waterhowever, the indicator pointer will start to rise until it finallytouches contact 37' of adjusting pointer 37. This then shortcircuits thesecondary winding of transformer 41, so that the impedance in serieswith relay R3 is reduced to a very low value, thus energizing the relay.The relay then operates, opening the energizing circuit of water controlvalve 28 at point 60. The soap supply still remains open, as long asterminal 57 is under power. If right from the start the bath containedsufiicient water, so that pointer 35 of the hygrometer had alreadyreached the required position, the relay would have prevented theenergization of the Water supply system, also right from the start, sothat the application of power to terminals 57 and 58 would have openedthe soap supply exclusively.

In this manner the desired relative humidity, set by means of pointer37, can be obtained in each case, after which the washing method can becontinued under optimum conditions. It is advisable to apply a washingperiod of approximately 8 minutes, in order to assure perfect results.

The washing method is followed by rinsing, preceded or not by drainageof the bath fluid. As soon as the predetermined washing time haselapsed, power Will be cut oft" from terminal 58, thus stopping pumpmotor 55 which is connected to it. Simultaneously power is applied toterminal 59, thus energizing air supply control valve 43 via closedrelay contact 61. A current also flows through relay coil R4; duehowever to the high impedance of the primary winding of transformer 40which is connected in series with a aforesaid coil, this current is soweak, that the relay can not operate. By the introduction of dry air viapipe 42 and control valve 43 into the measuring equipment 12, the latteris being dried, so that indicator pointer 35 starts receding and finallytouches contact 36 of adjuster pointer 36. The secondary winding oftransformer 40 is thereby short-circuited, reducing the impedance inseries with relay winding R4 to such a low value that it can no longerprevent the relay from operating. This opens the energizing circuit ofthe air supply system at 61. The hygrometer is thus automaticallyprepared in the correct manner for a following washing method.

The green and red pilot lamps, respectively 56 and 62, can be used assafety devices for the correct operation of the apparatus. Green pilotlamp 56 lights as long "as the mercury switch is closed. This is normalas long as pump 20 is in operation, producing a constant flow of fluidreaching safety device 26 via measuring equipment 12. Should this pilotlamp however remain lighted several minutes after the pump has stopped,this would indicate that evacuation opening 48 of cup 44 is clogged,preventing the draining away of the liquid.

The red pilot lamp lights as long as the water supply is opened. Shouldthis however last an abnormally long time, i.e. when pointer 35 hasalready reached contact 37' and the water supply nevertheless remainsopen, this water supply will immediately have to be shut off by means ofa manual cock (not shown).

It will be quite clear, that the above detailed description only relatesto one particular form of the many possible forms of embodiment of thisequipment according to the invention. Remaining within the scope of theinvention, it is obvious that either the detailed construction of thevarious elements or the manner in which these elements work together canbe modified in various ways, as long as the principles laid down in theclaims below 10 are maintained. The invention covers all these possiblealternatives.

What I claim is:

1. Dry cleaning apparatus in which the goods to be cleaned are washedand a dry cleaning solvent composi-. tion is circulated in a closedcirculation path, comprising a rotatable washing drum, a filter and apump in pipe communication with each other and to the drum, a humiditymeasuring device having an inlet and an outlet, a by-pass pipeinterconnecting an outlet of said pump and said inlet of said humiditymeasuring device to divert a small stream of circulating solventcomposition to said humidity measuring device, a reservoir for water, areservoir for washing materials, each of said reservoirs having anoutlet, control means responsive to said humidity measuring device toregulate the flow of said Water and of said washing materials to saidcirculating solvent composition, a mixing device for mixing said water,said washing materials and said circulating solvent composition, saidmixing device including a container provided with one outlet and fourinlets which are connected to the outlet of said first-mentionedreservoir, the outlet of said second-mentioned reservoir, the outlet ofsaid measuring device and the outlet of said pump respectively, and theoutlet of said mixing device being connected to said wash-ing drum.

2. Dry cleaning apparatus according to claim 1, in which twoelectrically operated valves are provided with the outlets of said firstand second reservoirs being connected to said mixing device by the firstand secondmentioned electrically operated valves respectively, saidvalves being each individually controlled.

3. Dry cleaning apparatus according to claim 1, in which the saidcontainer is formed as a cylindrical body fitted with an evacuationfunnel in its bottom, said first, second and third-mentioned inletsterminating in the top of said cylinderical body, with thefourth-mentioned inlet extending lengthwise through said cylindricalbody and terminating close to the opening of the funnel, and in which ajet pipe nozzle is provided mounted in said opening of the funnel.

4. Dry cleaning apparatus according to claim 1, in which a hygrometer isprovided connected to said humidity measuring device and which isuninfluenced by the vapours of said solvent composition but reacts onlyto the water vapours mixed therewith.

5. Dry cleaning apparatus according to claim 1, in which an electricallyoperated valve is provided, the said measuring device being mounted in acylindrical container fitted with a supply pipe which is coupled with asource of dry air by means of the electrically operated valve.

6. Dry cleaning apparatus according to claim 1, in which the saidhumidity measuring device is provided with a hygrometer which isuninfluenced by the vapours of said solvent composition but reacts onlyto the water vapours mixed therewith, and in which an adjustable contactdevice is provided for the hygrometer and which closes an electriccontact as soon as the measured humidity reaches a predetermined value,and another contact device closes a second electric contact as soon asthe measured humidity drops below a predetermined value.

7. Dry cleaning apparatus according to claim 1, in which the saidhumidity measuring device is provided with a hygrometer which is notinfluenced by the vapours of said solvent composition but reaches onlytothe water vapours mixed therewith, and in which said hygrometer isfitted with an indicator pointer moving along a graduated scale, and afurther pointer is provided manually adjustable along said scale, saidpointers having control parts of an electric contact device which isclosed as soon as the relative humidity indicated by said indicatorpointer reaches the value determined by said adjustable pointer.

8. Dry clean-ing apparatus according to claim 1, in which the saidhumidity measuring device is provided with a hygrometer which isuninfluenced by the vapours of said solvent composition but reacts onlyto the water vapours mixed therewith, and in which-the said measuringdevice is mounted in a cylindrical container fitted with a supply pipewhich is coupled with a source of dry air by means of "an electricallyoperated value, and a contact device closes an electric contact as soonas the measured humidity drops below a predetermined value, in whichcontrol means are provided including first and second electric contactsand first, second and third electrically operated valves, and saidfirst-mentioned electric contact being coupled with said first-mentionedelectrically toperated valve, whereas the second-mentioned electriccontact is coupled with said third-mentioned electrically operated valveso that when said first-mentioned electric contact is closed andfirst-mentioned valve is operated thus shutting off the air supply, andin which the control means includes a safety device incorporated in thepipe connecting said outlet of said humidity measurting device and saidthird-mentioned inlet of said mixing device, the safety devicecontrolling a third contact device which is coupled with saidfirst-mentioned electric contact and said first-mentioned electricallyoperated valve so that the water supply can only be opened when and aslong as a predetermined minimum quantity of solvent composition flowsfrom said humidity measuring device.

9. Dry cleaning apparatus according to claim 1, in which the saidhumidity measuring device is provided With a hygrometer which is notinfluenced by the vapours of said solvent composition but reacts only tothe water vapours mixed therewith, and in which the said measuringdevice is mounted in acy-lindrical container fitted with a supply pipewhich is coupled with a source of dry air by means of an electricallyoperated valve, and a contact device closes an electricrcontact as soonas the measured humidity drops below a predetermined value, and in whicha second contact device is provided constituted by a mercury switchwhich is operated by a pivoting lever capable of turning between twoextreme positions determined by stops, and to one end of which a smallfluid cup is attached, the latter tending by means of its weight and thefluid therein to move the lever towards one of its extreme positions atwhich the switch is closed, a counterweight return device pulling thelever towards its other extreme position at which the contact is open sothat as long as the cup contains a predetermined quantity of liquid, theswitch will be maintained closed by the weight of the cup and thepredetermined quantity of liquid, whereas the switch will be opened,closing the water supply, whrenever the quantity of liquid in the cupdrops below said predetermined value, the tilting fluid cup being fittedinside a container provided with an outlet pipe leading to the mixingdevice, the outlet of the measuring device ending; in the saidlast-mentioned container just above the cup.

References Cited in the file of this patent UNITED STATES PATENTS2,913,893 Mathews et a1. Nov. 24, 1959 2,940,287 Henderson June 14, 19602,967,084 Reitz Jan. 3, 1961

1. DRY CLEANING APPARATUS IN WHICH THE GOODS TO BE CLEANED ARE WASHEDAND A DRY CLEANING SOLVENT COMPOSITION IS CIRCULATED IN A CLOSEDCIRCULATION PATH, COMPRISING A ROTATABLE WASHING DRUM, A FILTER AND APUMP IN PIPE COMMUNICATION WITH EACH OTHER AND TO THE DRUM, A HUMIDITYMEASURING DEVICE HAVING AN INLET AND AN OUTLET, A BY-PASS PIPEINTERCONNECTING AN OUTLET OF SAID PUMP AND SAID INLET OF SAID HUMIDITYMEASURING DEVICE TO DIVERT A SMALL STREAM OF CIRCULATING SOLVENTCOMPOSITION TO SAID HUMIDITY MEASURING DEVICE, A RESERVOIR FOR WATER, ARESERVOIR FOR WASHING MATERIALS, EACH OF SAID RESERVOIRS HAVING ANOUTLET, CONTROL MEANS RESPONSIVE TO SAID HUMIDITY MEASURING DEVICE TOREGULATE THE FLOW OF SAID WATER AND OF SAID WASHING MATERIALS TO SAIDCIRCULATING SOLVENT COMPOSITION, A MIXING DEVICE FOR MIXING SAID WATER,SAID WASHING MATERIALS AND SAID CIRCULATING SOLVENT COMPOSITION, SAIDMIXING DEVICE INCLUDING A CONTAINER PROVIDED WITH ONE OUTLET AND FOURINLETS WHICH ARE CONNECTED TO THE OUTLET OF SAID FIRST-MENTIONEDRESERVOIR, THE OUTLET OF SAID SECOND-MENTIONED RESERVOIR, THE OUTLET OFSAID MEASURING DEVICE AND THE OUTLET OF SAID PUMP RESPECTIVELY, AND THEOUTLET OF SAID MIXING DEVICE BEING CONNECTED TO SAID WASHING DRUM.